Electrical connecting member for secondary battery

ABSTRACT

Disclosed herein is a connection member for secondary batteries to achieve the electrical connection in a battery pack including two or more cylindrical secondary batteries in a physical contact manner, the connection member including an outer circumferential contact part contacting an electrode terminal of a lower battery cell along the outer circumferential region of the electrode terminal of the lower battery cell, such that the outer circumferential contact part can be electrically connected to the electrode terminal of the lower battery cell in a surface contact manner and a central contact part contacting an electrode terminal of an upper battery cell or the central region of a sidewall of the battery pack for providing an elastic contact force to the entire connection member mounted between the electrode terminals of the respective battery cells or between the electrode terminals of the battery cells and the sidewall of the battery pack.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. application Ser. No.13/761,762, filed Feb. 7, 2013, which is a Divisional of U.S.application Ser. No. 13/611,752, filed on Sep. 12, 2012, which is aDivisional of U.S. application Ser. No. 12/669,410 filed on Jan. 15,2010, now U.S. Pat. No. 8,287,313, which is the National Phase of PCTInternational Application No. PCT/KR2008/004157 filed on Jul. 16, 2008,which claims priority under 35 U.S.C. 119(a) to Patent Application No.10-2007-0071389 filed in the Republic of Korea on Jul. 16, 2007, PatentApplication No. 10-2007-0103290 filed in the Republic of Korea on Oct.13, 2007, and Patent Application No. 10-2008-0060553 filed in theRepublic of Korea on Jun. 26, 2008. The entire contents of all of theabove applications are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to an electric connection member forsecondary batteries, and, more particularly, to a connection member forsecondary batteries to achieve the electrical connection in a batterypack including two or more cylindrical secondary batteries in a physicalcontact manner, the connection member including an outer circumferentialcontact part contacting an electrode terminal of a lower battery cellalong the outer circumferential region of the electrode terminal of thelower battery cell, such that the outer circumferential contact part canbe electrically connected to the electrode terminal of the lower batterycell in a surface contact manner, for minimizing the change ofresistance at the contact region against an external force andrestraining a possibility that the electrode terminal of the lowerbattery cell is depressed, and a central contact part contacting anelectrode terminal of an upper battery cell or the central region of asidewall of the battery pack for providing an elastic contact force tothe entire connection member mounted between the electrode terminals ofthe respective battery cells or between the electrode terminals of thebattery cells and the sidewall of the battery pack.

BACKGROUND OF THE INVENTION

As mobile devices have been increasingly developed, and the demand ofsuch mobile devices has increased, the demand of secondary batteries hasalso sharply increased as an energy source for the mobile devices.

Depending upon kinds of external devices in which the secondarybatteries are used, the secondary batteries may be used in the form of asingle battery or in the form of a battery pack having a plurality ofunit cells electrically connected to one another. For example,small-sized devices, such as mobile phones, can be operated for apredetermined period of time with the power and the capacity of onebattery. On the other hand, a secondary battery pack needs to be used inmiddle- or large-sized devices, such as laptop computers, portabledigital versatile disc (DVD) players, small-sized personal computers(PCs), electric vehicles, and hybrid electric vehicles, because highpower and large capacity are necessary for the middle- or large-sizeddevices.

The battery pack is manufactured by connecting a protection circuit to acore pack having a plurality of unit cells (secondary batteries)connected in series and/or in parallel to one another. When prismaticbatteries or pouch-shaped batteries are used as the unit cells, theprismatic batteries or the pouch-shaped batteries are stacked such thatlarge-sized surfaces of the prismatic batteries or the pouch-shapedbatteries face each other, and then electrode terminals of the prismaticbatteries or the pouch-shaped batteries are connected to one another byconnection members, such as bus bars. Consequently, when athree-dimensional secondary battery pack having a hexahedral structureis to be manufactured, the prismatic secondary batteries or thepouch-shaped secondary batteries are preferably used as unit cells ofthe secondary battery pack.

On the other hand, cylindrical secondary batteries generally haveelectric capacities larger than the prismatic secondary batteries or thepouch-shaped secondary batteries. However, it is difficult to arrangethe cylindrical batteries in a stacked structure due to the externalshape of the cylindrical secondary batteries. When the secondary batterypack is constructed generally in a line-type structure or in aplane-type structure, though, the cylindrical secondary batteries arestructurally more advantageous than the prismatic secondary batteries orthe pouch-shaped secondary batteries.

Consequently, a battery pack having a plurality of cylindrical secondarybatteries connected in series to or in parallel and series to oneanother is widely used in laptop computers, portable DVD players, andportable PCs. The secondary battery pack may be constructed in variouscore pack structures. For example, the core pack of the battery pack maybe generally constructed in a 2P(parallel)-3S(series) line-typestructure, a 2P-3S plane-type structure, a 2P-4S line-type structure, a2P-4S plane-type structure, a 1P-3S line-type structure, or a 1P-3Splane-type structure.

The parallel connection structure is achieved by adjacently arrangingtwo or more cylindrical secondary batteries in the lateral directionthereof, while electrode terminals of the cylindrical batteries areoriented in the same direction, and connecting the electrode terminalsof the cylindrical batteries to one another using connection members bywelding. The cylindrical secondary batteries connected in parallel toone other may be referred to as a “bank.”

The series connection structure is accomplished by arranging two or morecylindrical secondary batteries in the longitudinal direction thereofsuch that electrode terminals of the cylindrical batteries havingopposite polarities are successively disposed one after another, oradjacently arranging two or more cylindrical batteries in the lateraldirection thereof, while electrode terminals of the cylindricalbatteries are oriented in opposite directions, and connecting theelectrode terminals of the cylindrical secondary batteries to oneanother using connection members by welding.

The electrical connection between the cylindrical secondary batteries isgenerally achieved by spot welding using thin connection members, suchas metal plates (for example, nickel plates).

FIG. 1 typically illustrates a battery pack constructed in a 2P-3Splane-type structure in which batteries are electrically connected toone another by spot welding. For easy understanding, the couplingbetween the batteries constituting the battery pack of the 2P-3Splane-type structure is shown in an exploded view.

As shown in FIG. 1, three pairs of secondary batteries 20 and 21,connected in parallel to each other for each pair, are connected inseries to one another via metal plates 30 to constitute a core pack 10.

FIG. 2 is a typical view illustrating a battery module 50 in which aprotection circuit module is connected to the core pack of FIG. 1.

As shown in FIG. 2, secondary batteries 20 and 21 are connected to theprotection circuit module 90 via a cathode conducting wire 60 and ananode conducting wire 70 connected to the metal plates 30 and flexibleprinted circuit boards (FPCB) 80 connected to the conducting wires. Theelectrical connection between the metal plates 30 and the protectioncircuit module 90 is mostly achieved by soldering.

Generally, a battery pack using secondary batteries as unit cells isrepeatedly charged and discharged during the use of the battery pack,and the battery pack uses lithium secondary battery, which exhibits lowsafety in abnormal conditions, such as external impact, dropping,penetration of a needle-shaped body, overcharge, overcurrent, etc., as aunit cell. In order to solve such a safety-related problem, therefore, asafety element, such as a protection circuit module, is included in thebattery pack. The safety element acquires information, such as voltage,at a corresponding terminal connection region of the battery pack toperform a predetermined safety process, thereby securing the safety ofthe battery pack. Consequently, when the connection state of thecorresponding region is variable, for example, the resistance value ofthe terminal connection region changes due to vibration, the detectedinformation is inaccurate, and therefore, the safety element cannotperform the desired process. For this reason, the electrical connectionbetween the battery cells and the protection circuit in the battery packis generally achieved by soldering.

Also, it is necessary to connect a plurality of battery cells in seriesor in parallel to one another to constitute a high-power, large-capacitybattery pack. In addition, a stable coupling method that is capable ofminimizing the resistance change of the terminal connection region isrequired to uniformly maintain the efficiency of the battery pack.Generally, the electrical connection between the battery cells isachieved by soldering or welding, preferably spot welding.

However, the welding or soldering process between the battery cells hasthe following problems.

Specifically, the welding or soldering process requires worker's skilledtechnique and know-how. In addition, the control of parameters necessaryto decide the intensity of welding must be continuously performed. As aresult, the production process is complicated, and the production costsincrease, whereby the production efficiency lowers. Also, a shortcircuit may occur at the welded region, due to the vibration generatedfrom the battery pack or external impact applied to the battery pack, atthe time of directly welding or soldering the battery cells. Inaddition, electrical or thermal damage may be caused between the batterycells and the connection members, whereby the safety of the batteries isthreatened, and the defective product rate increases. Furthermore, whensome of the battery cells become defective, during the manufacturing oruse of the battery cells, all the battery cells constituting the batterypack must be discarded.

Consequently, there is a high necessity for a technology that is capableof substituting for the connection method based on such welding orsoldering, which threatens the safety of the batteries and requires acomplicated working process, and, at the same time, reusing theremaining battery cells, although some of the battery cells aredefective, while stably securing the connection structure between thebattery cells.

Meanwhile, for a battery pack using primary batteries, various attemptshave been made to achieve the electrical connection between therespective batteries. For example, Korean Patent No. 0413381 discloses atechnology for forming conductive coils at opposite ends of batterycases to electrically connect batteries to one another. U.S. Pat. No.525,037 discloses a technology for mounting metal plates, which are bentto exhibit elasticity, at opposite ends of batteries to achieveelectrical connection between the respective batteries.

However, the above-mentioned technologies have a problem in that it isrequired for connection members to exhibit elasticity enough to fix thebattery cells and stably connect electrode terminals to one another, andtherefore, connection members exhibiting low elasticity are limited inuse. Especially, the technology using the conduction coils has problemsin that the sectional area of a wire constituting each coil is small,and the connection length of the wire is relatively large, whereby theelectrical resistance increases. The increase of the electricalresistance causes power loss and increases the amount of heat generated,whereby the stable connection between the batteries may be obstructed.Also, for the technology using the metal plates that are bent to haveelasticity, the metal plates may lose their elasticity or break when anexcessive force is applied to the metal plates at the time of insertingthe battery cells into the pack case, or when the metal plates arerepeatedly used, with the result that, when external impact is appliedto the battery cells, the battery cells may be separated from the packcase or the electrical connection between the battery cells may be cutoff.

Furthermore, the above-mentioned connection member is limited to applyto the previously described secondary battery pack due to the variableconnection state at the corresponding region.

Also, in order to achieve the electric connection between the batterycells in a mechanical contact manner, without using welding orsoldering, it is required that partitions necessary to mount theconnection members to the pack case be located between the batterycells, as in the conventional arts. However, the provision of thepartitions increases the size of the battery pack, which is far from thelatest tendency to pursue the reduction in size, weight, and thickness.In addition, it is preferred for a battery pack including a plurality ofbattery cells to be under a uniform operating condition in the aspect ofthe operational efficiency. However, the operating conditions of thebattery cells mounted in the receiving parts divided by the partitionsmay be different from each other for the respective receiving parts,when external impact is applied to the battery pack, through theprovision of the partitions.

In this aspect, a method may be considered of mounting mechanicalcontact type connection members between the battery cells at a very highelastic pressing force in a structure having no partitions. In thismethod, however, a material, such as polymer resin, for the pack case isslowly deformed by stress during the use of the pack case for a longperiod of time, which is called a creep phenomenon. Consequently,excessively high elastic pressing force of the connection members causesthe occurrence of stress at the pack case, which leads to the creepphenomenon. As a result, the distance between the battery cellsgradually increases, and therefore, the electrical connection betweenthe battery cells is unstable. This phenomenon may be serious especiallyfor a device of which the long-term use is required. Consequently, theconnection method based on the primary batteries cannot be applied to abattery pack, based on secondary batteries, of which the long-term useis required through repeated charge and discharge, without anymodification.

Meanwhile, a cylindrical battery is constructed in a structure in whicha jelly-roll is mounted in a metal container, and a protruding cathodeterminal is formed at one end of the container while a flat anodeterminal is formed at the other end of the container. Since a capassembly is mounted to the top of the jelly-roll in a crimpingstructure, the cathode terminal region exhibits structural stabilityagainst an external force. On the other hand, since the jelly-rolldirectly faces the inner bottom of the container, the anode terminal(i.e., the bottom of the container) is deformed by an external force,with the result that a short circuit may occur between electrode platesof the jelly-roll.

In a battery pack including a plurality of battery cells, such a shortcircuit causes a very serious problem in the aspect of the safety. Theinventors of the present invention have experimentally confirmed thatsuch a short circuit occurred in a structure in which connectionmembers, such as nickel plates, are coupled to the electrode terminalsof the battery cells by welding.

Consequently, there is a high necessity to provide a connection memberfor secondary batteries that is capable of substituting for theconnection method based on welding or soldering, and securing the stableconnection structure between the battery cells and the safety of thebatteries while not causing the increase in size of the battery pack.

SUMMARY OF THE INVENTION

Therefore, the present invention has been made to solve the aboveproblems, and other technical problems that have yet to be resolved.

Specifically, it is an object of the present invention to provide aconnection member for secondary batteries that is capable of stablyachieving the electrical connection between two or more secondarybattery cells without performing a soldering or welding process, whichrequires a complicated working process, and constructed in a specificstructure in which the electrical connection thereof is possible, anassembly process is easily performed, and the connection member isfreely attached and detached as needed.

It is another object of the present invention to provide a connectionmember for secondary batteries that does not cause the increase in sizeof a battery pack and that is capable of stably maintaining theconnection between the battery cells, even when in use for a long periodof time, and securing the safety of the batteries against an externalforce.

In accordance with one aspect of the present invention, the above andother objects can be accomplished by the provision of a connectionmember for secondary batteries to achieve the electrical connection in abattery pack including two or more cylindrical secondary batteries in aphysical contact manner, the connection member comprising: an outercircumferential contact part contacting an electrode terminal of abattery cell located below the connection member (a lower battery cell)along the outer circumferential region of the electrode terminal of thelower battery cell, such that the outer circumferential contact part canbe electrically connected to the electrode terminal of the lower batterycell in a surface contact manner, for minimizing the change ofresistance at the contact region against an external force andrestraining a possibility that the electrode terminal of the lowerbattery cell is depressed; and a central contact part contacting anelectrode terminal of a battery cell located above the connection member(an upper battery cell) or the central region of a sidewall of thebattery pack for providing an elastic contact force to the entireconnection member mounted between the electrode terminals of therespective battery cells or between the electrode terminals of thebattery cells and the sidewall of the battery pack.

Consequently, the connection member for secondary batteries according tothe present invention does not need a welding or soldering process forelectrical connection between the electrode terminals of the batterycells. The connection between the battery cells is stably maintainedonly by the coupling of the connection member to the battery cells.Therefore, it is possible to prevent the occurrence of short circuits ofthe battery cells, which may be caused during soldering or welding.Also, the change in resistance at the connection regions does notdeviate from a desired degree of reliability although external impact isapplied to a battery pack, and it is possible to prevent the occurrenceof a short circuit of the lower battery cell due to the depression ofthe electrode terminal of the lower battery cell. At the same time, itis possible to easily perform a battery pack assembly process and toachieve stable coupling between the electrode terminals of the batterycells.

Also, when some of the battery cells are defective during the assemblyor the use of the battery pack, the battery cells may be easilyseparated from each other, with the result that it is possible to solvea problem in that all the battery cells constituting the battery packwill be discarded due to the defectiveness of some battery cells or theconnection member. Also, during the manufacture of the battery pack, nopartition is required when the connection member is mounted between thebattery cells. Consequently, the size of the battery pack is notincreased although the connection member is connected to the electrodeterminals of the battery cells without using welding or soldering.

Furthermore, the connection member is elastically connected to theelectrode terminals of the battery cells while being somewhat pressed,and therefore, the change in resistance at the connection regions doesnot deviate from a desired degree of reliability although externalimpact is applied to the battery pack. That is, the above-describedstructure enables a control member, such as a battery management unit(BMU), to accurately detect the temperature and voltage of the batterycells, whereby it is possible to secure the normal operation of thebattery. On the other hand, the elastically pressed state of theconnection member mounted at the corresponding region is not largeenough to cause a creep phenomenon of the pack case as previouslydescribed.

The connection member according to the present invention may be mountedbetween the respective electrode terminals of the battery cells toachieve the electrical connection between the battery cells or may bemounted between the electrode terminals of the battery cells and thesidewall of the battery pack.

In the former case, the connection member may be connected to theelectrode terminal of the lower battery cell in a physical contactmanner and may be connected to the electrode terminal of the upperbattery cell in a mechanical coupling manner. In the latter case, theconnection member may be connected to the electrode terminal of thelower battery cell in a physical contact manner and may be supported bythe sidewall of the battery pack.

A characteristic of the connection member according to the presentinvention is that the outer circumferential contact part contacts theelectrode terminal of the lower battery cell along the outercircumferential region of the electrode terminal of the lower batterycell, such that the outer circumferential contact part can beelectrically connected to the electrode terminal of the lower batterycell in the surface contact manner.

The inventors of the present invention have performed various tests onconnection members constructed in various structures to achieveelectrical connection in a physical contact manner and found that it isrequired to secure a maximum contact area, even when the position of theconnection member or the battery cells is changed, in order that thechange in resistance at the connection regions does not deviate from adesired degree of reliability although external impact is applied to abattery pack, and, it is required for the connection member to beconnected to the electrode terminal of the lower battery cell along theouter circumferential region of the lower battery cell in a surfacecontact manner with a large radius in order to secure such a maximumcontact area. That is, when the connection member is connected to theelectrode terminal of the lower battery cell along the outercircumferential region of the lower battery cell in the surface contactmanner with a large radius, as described above, the decrease of thecontact area is minimized although the position of the connection memberor the battery cells is changed due to external impact.

In the above description, the expression ‘outer circumferential region’is a concept including the outer circumference end of the electrodeterminal of the lower battery cell and the region extending from theouter circumference end of the electrode terminal toward the centralaxis of the electrode terminal. Consequently, the connection membercontacts the electrode terminal of the lower battery cell with thelargest radius through the outer circumferential contact part.

Also, since the outer circumferential contact part of the connectionmember contacts the outer circumferential region of the lower batterycell in the surface contact manner, as described above, it is possibleto minimize a possibility that the electrode terminal of the lowerbattery cell is depressed by the connection member and/or the electrodeterminal of the upper battery cell when an external force is applied tothe battery pack.

As previously described, the cylindrical secondary battery isconstructed in a structure in which the jelly-roll directly faces themetal container at the anode region, with the result that the electrodeterminal may be easily depressed by an external force. Preferably,therefore, the electrode terminal of the lower battery cell is an anode,and the electrode terminal of the upper battery cell is a cathode.

The prevention of the occurrence of a short circuit due to thedepression of the electrode terminal can be confirmed throughexperiments.

FIG. 3 is an X-ray fluoroscopic view illustrating a (conventional)battery pack constructed in a structure in which the battery module ofFIG. 2 is mounted in the pack case, and

FIG. 4 is an X-ray fluoroscopic view illustrating the change of thebattery pack after dropping the battery pack from a height of 1 m in astate in which the left side end of the battery pack is directed towardthe floor.

As shown in FIG. 4, the connection member (nickel plate) is coupled tothe anode terminal of the battery cell a and the cathode terminal of thebattery cell b by welding. When impact due to the dropping was appliedto the battery pack, the protruding cathode terminal applied strongimpact to the flat anode terminal through the nickel plate, with theresult that the anode terminal at the lower end of the metal containerwas depressed (see x region). FIG. 4 illustrates the structure in whichthe anode terminal of the battery cell a and the cathode terminal of thebattery cell b were spaced apart from each other again by a restoringforce of the nickel plate after the dropping of the battery pack.However, it can be seen that the anode terminal at the lower end of themetal container is partially depressed. The depressed anode terminalcontacted the corresponding region of the jelly-roll in the metalcontainer, with the result that a short circuit occurred.

On the other hand, FIG. 5 is an X-ray fluoroscopic view illustrating thechange of a battery pack constructed in a structure in which the cathodeterminal and the anode terminal are electrically connected to each otherby a connection member according to a preferred embodiment of thepresent invention in a physical contact manner after dropping thebattery pack under the same condition as the above

As shown in FIG. 5, the outer circumferential contact part of theconnection member is connected to the outer circumferential region ofthe anode terminal of the lower battery cell a in a surface contactmanner, and the central contact part of the connection member is coupledto the cathode terminal of the upper battery cell b in a mechanicalcoupling manner. Although strong impact was applied to the battery packdue to the dropping of the battery pack, a considerable amount of theimpact was dampened by the elastic structure of the central contactpart, and the remaining impact was transmitted toward the outercircumference of the anode terminal by the outer circumferential contactpart. As a result, the depression of the anode terminal, which occurredin FIG. 4, did not occur (see y region), and therefore, a short circuitof the jelly-roll did not occur.

As can be seen from the above-mentioned results of the experiments, theconnection member according to the present invention is capable ofeffectively preventing the occurrence of an internal short circuit dueto external impact by virtue of the structural characteristics of theouter circumferential contact part and the central contact part.

In a preferred embodiment, the outer circumferential contact part isformed generally in a shape corresponding to the outer circumferentialshape of the electrode terminal of the lower battery cell. Since theouter circumferential contact part is formed in the above-defined shape,the contact between the outer circumferential contact part and theelectrode terminal of the lower battery cell is achieved with thelargest radius as previously described. In this structure, it ispreferred for the outer circumferential contact part to have a contactinterface of a size equivalent to 10% to 70% of the surface area of theelectrode terminal of the upper battery cell. It is preferred toincrease the size of the contact interface for surface contact whenconsidering the resistance at the contact region; however, the increasein size of the outer circumferential contact part causes the decrease insize of the central contact part. Consequently, it is necessary for thecontact interface to be within the above-specified range.

Preferably, the outer circumferential contact part includes one or moredownward extensions for covering the upper-end side of the lower batterycell to securely maintain the coupling between the connection member andthe electrode terminal of the lower battery cell. Consequently, it ispossible to achieve more stable coupling between the connection memberand the lower battery cell by the provision of the downward extensions.The downward extensions may be formed in various shapes. For example,the downward extensions may be constructed in a variable skirt structurein which the downward extensions extend from the outer circumferentialcontact part. The variable skirt structure is bent in correspondence tothe outside of the lower battery cell, and therefore, the variable skirtstructure assists the connection member to be stably fixed to theelectrode terminal of the lower battery cell, even when an externalforce is applied to the battery pack. Of course, however, the downwardextensions may be constructed in a non-variable skirt structure.

Another characteristic of the connection member according to the presentinvention is that the central contact part contacts the electrodeterminal of the upper battery cell or the central region of the sidewallof the battery pack to provide an elastic contact force to the entireconnection member. Since the outer circumferential contact part isformed at the outer circumference of the connection member, such thatthe change in resistance at the connection regions does not deviate froma desired degree of reliability, and the depression of the electrodeterminal of the lower battery cell due to an external force isprevented, the central contact part is located at the central region ofthe connection member, and therefore, the connection instability is notcaused even when the position of the connection member or the batterycell is changed due to external impact. Furthermore, since the centralcontact part provides the elastic contact force to the entire connectionmember mounted between the respective battery cells or between thebattery cells and the sidewall of the battery pack, it is possible toachieve a desired electrical connection in the battery pack without theprovision of additional mounting parts, such as partitions, thereby notcausing the increase in size of the battery pack. Also, a considerableamount of the applied external impact is dampened by the elasticstructure to minimize the amount of the external impact transmitted tothe outer circumferential contact part, thereby preventing theoccurrence of a short circuit of the jelly-roll due to the depression ofthe electrode terminal of the lower battery cell as previouslydescribed.

In a preferred embodiment, the central contact part elasticallyprotrudes upward with respect to the outer circumferential contact part.The central contact part may protrude in various structures based on theshape of the electrode terminal of the upper battery cell correspondingto the central contact part or the shape of the side wall of the batterypack.

For example, when the central contact part is connected to the cathodeterminal of the upper battery cell, the central contact part may includea coupling part variably coupled to gas discharge ports or couplingopenings formed at the cathode terminal of the upper battery cell.

Generally, a plurality of gas discharge ports are formed at a cathodeterminal of a cylindrical secondary battery to discharge internal gas,generated when the battery cell is abnormal, out of the battery cell.Consequently, the coupling parts of the central contact part are coupledinto the gas discharge ports formed at the cathode terminal of the upperbattery cell to maintain the stable connection between the connectionmember and the upper battery cell when external impact or vibration isapplied to the battery pack.

The coupling parts may be constructed in various structures, which willbe described hereinafter in detail with reference to the relevantdrawings.

Preferably, the central contact part is constructed in an upwardprotruding bridge structure having openings.

From experiments on connection members constructed in variousstructures, the inventors of the present invention have found that, whenthe central contact part is constructed in the upward protruding bridgestructure having the openings, the central contact part provides anelastic contact force to the entire connection member in a limitedinstallation space. The bridge structure is easily deformed to bemounted to the corresponding region. On the other hand, the bridgestructure exhibits high resilience according to the elasticity based onthe properties of the material for the connection member. Also, thebridge structure disperses external impact, when the external impact isapplied to the battery pack, to minimize the amount of impacttransmitted to the lower battery cell, thereby restraining thedepression of the electrode terminal of the lower battery cell due tothe connection member.

The number and the shape of the openings may vary depending upon theshape of the bridge structure.

In a preferred embodiment, the opening includes one or more auxiliaryconnection parts connected to the electrode terminal of the upperbattery cell, the electrode terminal of the lower battery cell, or theelectrode terminals of the upper and lower battery cells while beingelastically pressed.

The auxiliary connection parts further increase the elastic force of theconnection member. In addition, the auxiliary connection parts preventthe occurrence of an instantaneous short circuit of the electrodeterminal, when an external force, such as vibration or bending, isapplied to the battery pack.

Preferably, the auxiliary connection parts are tapered downward orupward from the inside of the outer circumferential contact part.

In accordance with another aspect of the present invention, there isprovided a connection member for secondary batteries to electricallyconnect a plurality of secondary battery cells, wherein the connectionmember is located between the battery cells arranged in the longitudinaldirection or in both the longitudinal direction and the lateraldirection, the connection member is connected, in an elastic contactmanner, to a lower electrode terminal of the front battery cell in thelongitudinal direction or to an upper electrode terminal of the rearbattery cell in the longitudinal direction, and the connection member iselastically pressed while the connection member is located between thebattery cells.

Hereinafter, several concrete examples of the connection member forsecondary batteries will be described.

In a first preferred embodiment, the connection member comprises aterminal connection unit for connecting the battery cells arranged inthe longitudinal direction in series to each other, and the terminalconnection unit comprises: (a) an outer circumferential contact partconfigured to correspond to the external shape of an electrode terminalof a lower battery cell, the outer circumferential contact partcontacting the electrode terminal of the lower battery cell at a regionadjacent to the outer circumference of the electrode terminal, the outercircumferential contact part having a predetermined width; (b) upwardprotruding parts tapered upward from the outer circumferential contactpart toward a central axis of the terminal connection unit forelastically supporting the lower battery cell; and (c) protrudingcoupling parts connected to the respective upward protruding parts in abridge structure, the protruding coupling parts protruding such that theprotruding coupling parts can be elastically coupled to a predeterminedregion of the upper battery cell.

Consequently, in a battery pack constructed in a structure in which aplurality of battery cells arranged in the longitudinal direction inseries connection to each other are mounted in a pack case, theprotruding coupling parts are connected to the respective upwardprotruding parts in the bridge structure, and therefore, it is possiblefor the connection member to easily electrically connect electrodeterminals of the battery cells in the elastic contact manner.

Preferably, the terminal connection unit further comprises a pluralityof auxiliary connection parts tapered downward and/or upward from theinside of the outer circumferential contact part.

The auxiliary connection parts further increase the elastic force of theconnection member and prevent the occurrence of an instantaneous shortcircuit of the electrode terminal, when an external force, such asvibration or bending, is applied to the battery pack.

Each upward-tapered auxiliary connection part is constructed in astructure in which the end of each upward-tapered auxiliary connectionpart is inclined toward the central axis of the connection member to aheight higher than that of the outer circumferential contact part. Theauxiliary connection parts extending upward to the height higher thanthat of the outer circumferential contact part can elastically supportthe upward protruding parts while the connection member is in contactwith the electrode terminal of the lower battery cell. Also, theupward-tapered auxiliary connection parts remain connected to theelectrode terminal of the upper battery cell. Consequently, theupward-tapered auxiliary connection parts prevent the occurrence of aninstantaneous short circuit due to the unstable connection state when anexternal force is applied to the battery pack, as previously described.Furthermore, when the number of the upward-tapered auxiliary connectionparts is two or more, the above-mentioned effects are more stablyprovided.

On the other hand, each downward-tapered auxiliary connection part isconstructed in a structure in which the end of each downward-taperedauxiliary connection part is inclined toward the central axis of theconnection member to a height lower than that of the outercircumferential contact part to obtain the above-mentioned effects.

In this case, the upward-tapered auxiliary connection parts may contactthe electrode terminal of the upper battery cell (a), and thedownward-tapered auxiliary connection parts may contact the electrodeterminal of the lower battery cell (b).

In a preferred example, the upward protruding parts extend from theupper inside and the lower inside of the outer circumferential contactpart such that the upward protruding parts are tapered upward from theouter circumferential contact part toward the central axis of theconnection member. Consequently, the upward protruding parts can beeasily inserted into predetermined regions formed at the electrodeterminal of the battery cell, and the outer circumferential contact partcan elastically contact the lower battery cell.

Preferably, the protruding coupling parts are formed at the left sideand the right side, respectively, at a right angle to connection regionsbetween the outer circumferential contact part and the upward protrudingparts. Also, the protruding coupling parts are connected to therespective upward protruding parts in the bridge structure.Consequently, it is possible to achieve more elastic coupling betweenthe protruding coupling parts and predetermined regions of the batterycell.

The predetermined regions of the battery cell means regions located atthe outside of the electrode terminal of the battery cell. For example,the predetermined regions may include gas discharge port regions formedat the outside of the electrode terminal to discharge internal gas,generated when the battery cell is abnormal, out of the battery cell.

The shape of the protruding coupling parts is not particularlyrestricted so long as the protruding coupling parts are easily coupledto the predetermined regions of the electrode terminal of the batterycell. For example, the protruding coupling parts may be constructed in astructure in which two or more bridges connecting the respectiveprotruding coupling parts are arranged in a symmetrical fashion, therebyproviding more elastic coupling force through the protruding couplingparts constructed generally in the more elastic structure.

For example, the top of each upward protruding part protrudes upward inthe vertical sectional shape thereof such that the respective upwardprotruding parts can be easily inserted into predetermined regions ofthe electrode terminal. In this case, the respective upward protrudingparts are more easily inserted into the predetermined regions of theelectrode terminal, and the contact force between the bridges connectedto the upward protruding part and the electrode terminal of the batterycell is further improved after the insertion of the respective upwardprotruding parts into the predetermined regions of the electrodeterminal.

As previously described, the downward or upward tapered auxiliaryconnection parts are formed at the inside of the outer circumferentialcontact part, and therefore, it is possible for the auxiliary connectionparts to further increase the elastic force of the connection member andto prevent the occurrence of an instantaneous short circuit of theelectrode terminal, when an external force, such as vibration orbending, is applied to the battery pack.

In another example, ends of the respective auxiliary connection partsare bent in the direction opposite to the taper direction of thecorresponding auxiliary connection parts. Consequently, it is possibleto prevent the ends of the auxiliary connection parts to damage, forexample scratch, the electrode terminal of the battery cell or a workerto be injured during the assembly of the battery pack.

In a second preferred embodiment, the connection member is constructedin a structure in which the connection member is located between theanode terminal of the battery cell and the sidewall of the battery packin a physical contact manner, and the physical contact type connectionmember comprises terminal connection units for electrically connectingtwo or more battery cells arranged in the lateral direction in aphysical contact manner, and each of the terminal connection unitscomprises: (a) an outer circumferential contact part configured tocorrespond to the external shape of an electrode terminal of thecorresponding battery cell, the outer circumferential contact partcontacting the electrode terminal of the corresponding battery cell at aregion adjacent to the outer circumference of the electrode terminal,the outer circumferential contact part having a predetermined width; and(b) upward protruding parts tapered upward from the outercircumferential contact part toward a central axis of each terminalconnection unit for elastically supporting the corresponding batterycell, the terminal connection units being electrically connected to eachother in correspondence to the number of the battery cells arranged inthe lateral direction.

In a battery pack constructed in a structure in which a plurality ofbattery cells are laterally arranged in two or more rows in a pack casewhile the battery cells are electrically connected to one another, it ispossible for the connection member to easily electrically connectelectrode terminals of the battery cells arranged in the lateraldirection (in parallel or in series) of the ends of the battery rows ina physical contact manner.

In this case, each of the terminal connection units may further includeauxiliary connection parts tapered downward from the inside of the outercircumferential contact part such that the terminal connection units canbe elastically connected to the corresponding electrode terminals.

In a third preferred embodiment, the connection member is constructed ina structure in which the connection member is located between the anodeterminal of the battery cell and the sidewall of the battery pack in anelastic physical contact manner, and the connection member comprisesterminal connection units for electrically connecting two or morebattery cells arranged in the lateral direction in a physical contactmanner, each of the terminal connection units comprising: (a) an outercircumferential contact part configured to correspond to the externalshape of an electrode terminal of the corresponding battery cell, theouter circumferential contact part contacting the electrode terminal ofthe corresponding battery cell at a region adjacent to the outercircumference of the electrode terminal, the outer circumferentialcontact part having a predetermined width; (b) upward protruding partstapered upward from the outer circumferential contact part toward acentral axis of each terminal connection unit for elastically supportingthe corresponding battery cell; (c) a pressing part protruding from theupward protruding parts to a predetermined height toward the centralaxis of each terminal connection unit for achieving the physical contactbetween the battery cells and the connection member; and (d) a depressedpart formed on the central axis of each terminal connection unit in adepressed shape by a depth less than the sum of the height of the upwardprotruding parts and the height of the pressing part, the terminalconnection units being electrically connected to each other incorrespondence to the number of the battery cells arranged in thelateral direction.

For example, the upward protruding part may be provided with two or morecut-off parts, having a predetermined width, formed toward the centralaxis of each terminal connection unit for controlling an elastic force.Of course, the upward protruding part exhibits the elastic forcealthough the cut-off parts are not provided at the upward protrudingpart. However, a desired elastic force may be changed depending upon thetype of the battery pack. Consequently, it is preferred to appropriatelycontrol the elastic force by forming the cut-off parts at the upwardprotruding part. Also, it is preferred for the cut-off parts to bearranged about the central axis of the connection member in asymmetrical structure such that the elastic force is not concentrated atone side of the upward protruding part but uniformly distributed. Thecut-off parts may be arranged in various shapes. For example, thecut-off parts are arranged in the shape of a whirlpool to effectivelyprovide a flexible elastic force.

In a fourth preferred embodiment, the connection member comprises aterminal connection unit for connecting the battery cells arranged inthe longitudinal direction in series to each other, the terminalconnection unit comprising: (a) an outer circumferential contact partconfigured to correspond to the external shape of the electrode terminalof the lower battery cell, the outer circumferential contact partcontacting the electrode terminal of the lower battery cell at a regionadjacent to the outer circumference of the electrode terminal, the outercircumferential contact part having a predetermined width; (b) upwardprotruding parts tapered upward from the outer circumferential contactpart toward a central axis of the terminal connection unit forelastically supporting the lower battery cell; and (c) protrudingcoupling parts protruding from the upward protruding parts to apredetermined height such that the protruding coupling parts can becoupled to the electrode terminal of the upper battery cell.

Consequently, in a battery pack constructed in a structure in which aplurality of battery cells arranged in the longitudinal direction inseries connection to each other are mounted in a pack case, it ispossible for the connection member to easily electrically connectelectrode terminals of the battery cells in an elastic contact manner.

The terminal connection unit may further comprise a depressed contactpart disposed on the central axis of the terminal connection unit suchthat the depressed contact part is depressed to a predetermined depthfrom the protruding coupling parts, the depressed contact partcontacting the electrode terminal of the upper battery cell.

The shape of the protruding coupling parts is not particularlyrestricted so long as the protruding coupling parts are easily coupledto the predetermined regions of the electrode terminal of the batterycell. For example, the protruding coupling parts may be constructed in astructure in which two or more bridges connecting the upward protrudingparts and the depressed contact part are arranged in a symmetricalfashion, thereby providing a high coupling force through the protrudingcoupling parts constructed generally in the more elastic structure.

As an example, the protruding coupling parts may be formed approximatelyin the vertical sectional shape of “∩” to be easily inserted into thepredetermined regions of the electrode terminal of the battery cell. Inthis case, a process for coupling the protruding coupling parts to thepredetermined regions of the electrode terminal of the battery cell ismore easily carried out. After the coupling between the protrudingcoupling parts and the predetermined regions of the electrode terminalof the battery cell, the protruding coupling parts do not easilyseparate from the predetermined regions of the electrode terminal of thebattery cell even due to external vibration. According to circumstances,each protruding coupling part may be provided at one side thereof with acoupling protrusion, which protrudes toward the central axis of eachterminal connection unit, to further increase the coupling between theprotruding coupling parts and the predetermined regions of the electrodeterminal of the battery cell.

The coupling protrusion may be constructed in various structures. Forexample, the coupling protrusion may be constructed in a structure inwhich the inner end of each protruding coupling part is bent toward thecentral axis of the connection member, or the coupling protrusion mayprotrude from the inner side of each protruding coupling part in theshape of a hemispherical protrusion. However, the coupling protrusion isnot limited to the above-specified structure.

Since the protruding coupling parts are constructed in a structure inwhich the plurality of bridges are arranged in the symmetrical fashion,and the protruding coupling parts are formed approximately in thevertical sectional shape of “∩,” as previously described, elasticinsertion and coupling of the protruding coupling parts are achievedirrespective of the coupling protrusions formed at the sides of therespective protruding coupling parts, at the time of coupling theprotruding coupling parts to the predetermined regions of the electrodeterminal of the battery cell.

According to circumstances, the connection member may further includeauxiliary connection parts extending downward from the ends of therespective upward protruding parts between the respective bridgesconnecting the upward protruding parts and the depressed contact part.Consequently, as previously described, the elastic force of the upwardprotruding parts is further increased, and the occurrence of aninstantaneous short circuit of the electrode terminal is prevented whenan external force, such as vibration or bending, is applied to thebattery pack.

In a fifth preferred embodiment, the connection member comprises aterminal connection unit for connecting the battery cells arranged inthe longitudinal direction in series to each other, a coupling openingbeing formed in at least one electrode terminal of the battery cells,the terminal connection unit comprising: (a) an outer circumferentialcontact part configured to correspond to the external shape of anelectrode terminal of a lower battery cell, the outer circumferentialcontact part contacting the electrode terminal of the lower battery cellat a region adjacent to the outer circumference of the electrodeterminal, the outer circumferential contact part having a predeterminedwidth; (b) upward protruding parts tapered upward from the outercircumferential contact part toward a central axis of the terminalconnection unit for elastically supporting the lower battery cell; and(c) coupling parts formed on the respective upward protruding parts suchthat the coupling parts can be elastically coupled into the couplingopening formed in the at least one electrode terminal of the batterycells.

Consequently, the connection member forms the stable connectionstructure for electrical connection only through the coupling betweenthe connection member and the electrode terminals of the battery cells,and therefore, the change in resistance at the connection regions doesnot deviate from a desired degree of reliability although externalimpact is applied to the battery pack. At the same time, it is possibleto easily perform a battery pack assembly process and to achieve stablecoupling between the electrode terminals of the battery cells.

Also, the coupling opening is formed in the corresponding electrodeterminal of the battery cell such that the connection member can bemounted to the corresponding electrode terminal of the battery cellthrough the coupling opening. Consequently, applicable structures orshapes of the connection member may be further diversified, and theconnection member may be constructed in a simpler structure.

For example, the connection member may be constructed in a structure inwhich the battery cell includes a protruding cathode terminal, and aplurality of gas discharge ports are formed at the protruding parts ofthe cathode terminal in the circumferential direction of the cathodeterminal, and the coupling opening is formed at the central region ofthe cathode terminal.

The coupling opening, which is configured to be coupled to theconnection member, is easily formed at the protruding cathode terminal,and therefore, the coupling opening can be easily applied to acylindrical battery including such a protruding cathode terminal. Also,the plurality of the gas discharge ports, which are arranged about thecoupling opening located at the central region of the electrode terminalin the circumferential direction thereof, effectively dischargehigh-pressure gas in the battery cell, as previously described, therebysecuring the safety of the battery cell.

However, the coupling opening is coupled to the connection member in themechanical coupling manner, with the result that the coupling opening isnot completely sealed by the connection member. Consequently, thecoupling opening may also function as the gas discharge port. In thisstructure, no gas discharge port may be formed at the protruding part ofthe cathode terminal. This structure must be interpreted to be includedin the scope of the prevent invention.

The coupling opening may be constructed in various structures or shapes.For example, the coupling opening may be constructed in a cross-shapedstructure in which two slits having long and short sides are formed atthe central region of the outer circumference of the electrode terminalof the battery cell, on the plane of the electrode terminal of thebattery cell, such that the two slits intersect at right angles.

Consequently, it is possible to easily couple battery cells to eachother using a connection member including a coupling part formed in ashape corresponding to that of the long side. The coupling part of theconnection member is inserted through the long side of the couplingopening, and is then rotated to a position where the coupling part ofthe connection member becomes parallel to the short side of the couplingopening, thereby achieving the elastic coupling between the connectionmember and the corresponding battery cell. Consequently, it is possibleto simply and easily achieve the coupling between the connection memberand the corresponding battery cell and, at the same time, the electricalconnection between the connection member and the corresponding batterycell.

As another example, the coupling opening may be constructed in astructure in which two arc-shaped slits are disposed about the centralaxis of the electrode terminal in a symmetrical fashion.

The coupling parts, of the connection member, horizontally bent in thelongitudinal direction of the slits such that the coupling parts areconstructed approximately in the vertical sectional shape of “

” are inserted into the two arc-shaped slits disposed in a symmetricalfashion, and are then rotated such that the horizontally bent portionsof the “

” shaped coupling parts are elastically connected to the lower end ofthe electrode terminal having no slits, whereby the stable couplingbetween the connection member and the battery cell is achieved.

The coupling parts may be bent such that ends of the coupling partsprotrude upward. In this structure, the coupling parts can be easilyinserted into the coupling opening of the battery cell, therebyachieving the electrical connection between the connection member andthe battery cell.

Preferably, the coupling parts extend from the respective upperprotruding parts, such that the coupling parts are disposed in asymmetrical fashion, whereby more elastic coupling between the couplingparts and the coupling opening of the corresponding battery cell isachieved.

The upward protruding parts extend from the upper inside and the lowerinside of the outer circumferential contact part such that the upwardprotruding parts are tapered upward from the outer circumferentialcontact part toward the central axis of the connection member.Consequently, the upward protruding parts can be easily inserted intopredetermined regions formed at the electrode terminal of the batterycell, and the outer circumferential contact part can elastically contactthe lower battery cell.

The terminal connection unit may further comprise a plurality ofauxiliary connection parts tapered downward and/or upward from theinside of the outer circumferential contact part.

In a sixth preferred embodiment, the connection member comprises aterminal connection unit for connecting the battery cells arranged inthe longitudinal direction in series to each other, and the terminalconnection unit comprises: (a) an outer circumferential contact partconfigured to correspond to the external shape of an electrode terminalof a battery cell located below the connection member (a lower batterycell), the outer circumferential contact part contacting the electrodeterminal of the lower battery cell at a region adjacent to the outercircumference of the electrode terminal, the outer circumferentialcontact part having a predetermined width; (b) upward protruding partstapered upward from the outer circumferential contact part toward acentral axis of the terminal connection unit for elastically supportingthe lower battery cell; and (c) a central contact part contacting anelectrode terminal of a battery cell located above the connection member(an upper battery cell), the terminal connection unit being constructedin a structure in which cut-out parts are formed at the upwardprotruding part and the central contact part, such that the cut-outparts extend from the upward protruding part to the central contact partand successively extend from the central contact part to the upwardprotruding part, to increase an elastically supporting force withrespect to the electrode terminal of the battery cell.

Since the connection member is constructed in a structure in which thecut-out parts are formed at the upward protruding part and the centralcontact part such that the cut-out parts extend from the upwardprotruding part to the central contact part and successively extend fromthe central contact part to the upward protruding part, the elasticallysupporting force with respect to the electrode terminal of the batterycell is increased, and therefore, the change in resistance at theconnection regions does not deviate from a desired degree of reliabilityalthough external impact is applied to the battery pack. Furthermore, itis possible to prevent the occurrence of a short circuit of the lowerbattery cell due to the depression of the electrode terminal of thelower battery cell.

Also, the connection member is elastically connected to the electrodeterminals of the battery cells while being somewhat pressed, and thecut-out parts reduce the elasticity of the upward protruding parts, withthe result that the upward protruding parts become more flexible.Consequently, the change in resistance at the connection regions doesnot deviate from a desired degree of reliability although externalimpact is applied to the battery pack.

Preferably, the central contact part has a contact interface of a sizeequivalent to 20% to 80% of the surface area of the electrode terminalof the upper battery cell. It is preferred to increase the size of thecontact interface for surface contact when considering the resistance atthe contact region; however, the increase in size of the central contactpart causes the decrease in size of the outer circumferential contactpart. Consequently, it is necessary for the contact interface to bewithin the above-specified range.

For example, the outer circumferential contact part and the centralcontact part may be electrically connected to the anode terminal and thecathode terminal of the battery cells, respectively, in a physicalcontact manner. That is, the cathode terminal of one cylindrical batterycell is electrically connected to the central contact part, which isconnected to the upward protruding parts of the connection member whilethe central contact part is surrounded by the upward protruding parts,and the anode terminal of the other cylindrical battery cell iselectrically connected to the outer circumferential contact part, whichis formed, with a predetermined width, at a region adjacent to the outercircumference of the connection member.

The cut-out parts are characteristic structures that are formed at theupper protruding part and the central contact part to make the upperprotruding part flexible. For example, each of the cut-out parts may beconstructed in a structure in which a cut-out start point and a cut-outend point form an angle of 20 to 160 degrees under a condition that eachof the cut-out parts does not reach the central axis of the connectionmember. Preferably, the cut-out start point and the cut-out end pointform an angle of 90 degrees.

The cut-out parts may be constructed in various structures. For example,the cut-out parts may be constructed in a bridge structure. Thebridge-structured cut-out parts can be easily formed at the upperprotruding part and the central contact part. Also, thebridge-structured cut-out parts can effectively provide flexibility tothe upper protruding part.

According to circumstances, the cut-out parts may be constructed in astructure in which each cut-out part has two or more end points withrespect to one cut-out start point. In this structure, several cut-outparts are formed at the upper protruding part, whereby the upperprotruding part exhibits greater flexibility.

Preferably, the distance between the central axis of the connectionmember and the region of each cut-out part where each cut-out part isthe nearest to the central axis of the connection member is 10 to 50% ofthe width of the central contact part. When the distance between thecentral axis of the connection member and the region of each cut-outpart where each cut-out part is the nearest to the central axis of theconnection member is too large as compared with the width of the centralcontact part, the overall size of the cut-out parts decreases, with theresult that the flexibility of the upper protruding part greatlydecreases. On the other hand, when the distance between the central axisof the connection member and the region of each cut-out part where eachcut-out part is the nearest to the central axis of the connection memberis too small as compared with the width of the central contact part, theoverall elasticity of the connection member excessively decreases, whichis not preferred.

Meanwhile, the structure of the cut-out parts is not particularlyrestricted so long as the cut-out parts are constructed in a structurein which the cut-out parts extend from the upward protruding part to thecentral contact part and successively extend from the central contactpart to the upward protruding part. Preferably, the respective cut-outparts pass through the uppermost portion of the upward protruding part.In this case, the flexibility of the upward protruding part furtherincreases, since respective cut-out parts pass through the uppermostportion of the upward protruding part.

For example, two or more cut-out parts may be radially arranged aboutthe central axis of the connection member in a symmetrical structure.The symmetrically radial cut-out parts are advantageous in that thesymmetrically radial cut-out parts can be easily formed at theconnection member. Furthermore, since the number of the cut-out parts istwo or more, it is possible to control the flexibility of the upwardprotruding part to a desired degree.

Also, it is preferred to adjust the size of the cut-out parts inconsideration of the thickness of the connection member such that theupward protruding part exhibits appropriate flexibility as well aselasticity. For example, the cut-out parts may be cut out with a widthequivalent to 50 to 300% of the thickness of the connection member. Thewidths of the respective cut-out parts are spaces formed at theconnection member by cutting out portions of the connection member. Thewidths of the respective cut-out parts enable the upward protruding partto exhibit appropriate flexibility as well as elasticity whilepreventing the deformation or the breakage of the upward protrudingpart.

According to circumstances, the cut-out parts may be formed at theconnection member in the shape of a line or slit.

In the first, fourth, fifth, and sixth preferred embodiments of theconnection member, among the above-described illustrative examples ofthe connection member, the connection member may include two or moreterminal connection units connected to each other to simultaneouslyachieve the connection in series between the battery cells arranged inthe longitudinal direction and the connection in parallel betweenbattery cells arranged in the lateral direction. Consequently, theconnection member may be constructed in a structure that is applicableto a series-connection and parallel-connection type battery pack as wellas a series-connection type battery pack.

Also, in the first to sixth preferred embodiments of the connectionmember, the terminal connection unit may be provided at one side thereofwith a circuit connection terminal part. The circuit connection terminalpart may be an input and output terminal for power supply, a detectionterminal for voltage detection, or a combination thereof. The circuitconnection terminal part may be formed in various shapes. For example,circuit connection terminal part may be formed in the shape of a stripextending from the outer circumferential contact part. The strip-shapedcircuit connection terminal part may be bent such that the circuitconnection terminal part is brought into tight contact with the side ofthe lower battery cell while the connection member is mounted to thelower battery cell.

In the above-described illustrative examples of the connection member,the width of the outer circumferential contact part contacting thebattery cell is preferably 5 to 30% of the radius of the terminalconnection unit. When the contact width of the outer circumferentialcontact part is less than 5%, the resistance at the contact regionincreases due to the small contact area. Also, the electrode terminal ofthe battery cell becomes out of position due to external impact, withthe result that the electrical connection may be easily cut off. On theother hand, when the contact width of the outer circumferential contactpart exceeds 30%, the sizes of the remaining parts, including the upwardprotruding parts, decrease, with the result that it is difficult toprovide a predetermined elastic force, and it is difficult to couple theprotruding coupling parts to the corresponding regions of the batterycell.

Also, the respective upward protruding parts preferably have a widthequivalent to 20 to 60% of the radius of the terminal connection unitand a tilt angle of 5 to 30 degrees. When the width of the respectiveupward protruding parts is less than 20% of the radius of the terminalconnection unit, it is difficult to provide a predetermined elasticforce, as previously described. On the other hand, when the width of therespective upward protruding parts exceeds 60% of the radius of theterminal connection unit, the areas of the contact parts contacting theelectrode terminals of the battery cells are relatively reduced, withthe result that a desired electrical connection is not achieved. Also,when the tilt angle of the respective upward protruding parts is lessthan 5 degrees to the lower end of the terminal connection unit, i.e.,the outer circumferential contact part, it is difficult to provide apredetermined elastic force against external impact. On the other hand,when the tilt angle of the respective upward protruding parts exceeds 30degrees, the inner space of the battery pack is reduced, and therespective upward protruding parts may break when external pressure isapplied to the respective upward protruding parts.

Also, the protruding coupling parts (or the coupling parts) preferablyhave a height equivalent to 30 to 70% of the total height of theconnection member. When the height of the protruding coupling parts isless than 30%, which means that the size of the protruding regions issmall, it is difficult to couple the protruding coupling parts topredetermined regions of the electrode terminal of the battery cell. Onthe other hand, when the height of the protruding coupling parts exceeds70%, it is required to further increase the inner space of the batterypack, whereby the size of the battery pack increases.

Also, the auxiliary connection parts are preferably inclined upward ordownward at an angle of 20 to 70 degrees to the horizontal section ofthe connection member. When the auxiliary connection parts are inclinedat an angle of less than 20 degrees, it is difficult for the auxiliaryconnection parts to maintain their elasticity when the auxiliaryconnection parts come into contact with the electrode terminal of thebattery cell. On the other hand, when the auxiliary connection parts areinclined at an angle of more than 70 degrees, the auxiliary connectionparts may damage, for example scratch, the electrode terminal, or theauxiliary connection parts may break during the assembly or the use ofthe battery pack.

In a preferred embodiment, the connection member is characterized inthat the outer circumferential contact part is further provided at theouter circumference thereof with one or more downward extensionsconstructed in a structure to partially cover the upper-end side of thelower battery cell. As previously described, the downward extensions maybe constructed in a variable skirt structure or in a non-variable skirtstructure.

Since the downward extensions are constructed in a structure topartially cover the upper-end side of the lower battery cell, it ispossible to prevent the connection member from deviating in positionfrom the lower battery cell due to external impact, and therefore, amore stable connection is achieved.

Preferably, the one or more downward extensions are arranged along theouter circumference of the outer circumferential contact part in asymmetrical structure. Consequently, the prevention of the connectionmember from deviating in position from the lower battery cell and thestable connection is more effectively achieved.

The length of the downward extensions is not particularly restricted solong as the downward extensions are constructed in a structure toprovide the above-mentioned effects. For example, the downwardextensions may have a length equivalent to 20 to 150% of the totalheight of the connection member.

Meanwhile, the connection member, which is constructed in variousstructures as previously described, may be manufactured in a single bodyby pressing a conductive sheet. Specifically, the conductive sheet ispunched or rolled according to the shape of the connection member, andtherefore, it is possible to easily and simply manufacture theconnection member having a specific structure.

Preferably, the connection member is used especially for cylindricalbattery cells. In this case, the specific regions of the connectionmember are generally constructed in a concentric circle structure, whichcorresponds to the shape of the electrode terminal of each cylindricalbattery cell, with the result that the contact area therebetween ismaximized.

In accordance with another aspect of the present invention, there isprovided a battery pack constructed in a structure in which theconnection member is mounted between electrode terminals of batterycells to achieve the electrical connection between the battery cells.

The battery pack may be constructed in a structure in which a pluralityof battery cells are electrically connected to one another in rows in apack case. The number of the rows may be one or more.

The connection member may be used to electrically connect the batterycells arranged in the longitudinal direction in each row. In a structureincluding two or more battery rows, the connection member may be used toelectrically connect the battery cells (bank) arranged in the lateraldirection.

When the connection member is used only for the electrical connection ofthe bank, for example, the battery pack may be manufactured in astructure in which battery cells are mounted in a pack case includingreceiving parts constructed such that two or more secondary batterycells are mounted in the respective receiving parts while being adjacentto each other in the lateral direction, and the connection member iscoupled to a sidewall contacting electrode terminals of the batterycells, among sidewalls constituting the pack case, such that the outercircumferential contact parts of the connection member is directedtoward the electrode terminals of the battery cells.

The battery pack according to the present invention may be used as, butis not limited to, a power source for household electric appliances,such as portable DVD players, small-sized PCs, etc., requiring highpower and large capacity.

More preferably, the battery pack according to the present invention isused as a power source for laptop computers. In accordance with afurther aspect of the present invention, therefore, there is provided alaptop computer including the battery pack as a power source.

The general structure of the laptop computers and a method ofmanufacturing the same are well known in the art to which the presentinvention pertains, and therefore, a further description thereof willnot be given.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is an exploded view illustrating the coupling between batterieselectrically connected to each other by conventional connection members,such as metal plates;

FIG. 2 is a typical view illustrating a battery module in which aprotection circuit module is connected to a core pack of FIG. 1;

FIG. 3 is an X-ray fluoroscopic view illustrating a battery packconstructed in a structure in which the battery module of FIG. 2 ismounted in a pack case;

FIGS. 4 and 5 are X-ray fluoroscopic views respectively illustrating thechange of the battery pack of FIG. 3 and a battery pack constructed byusing a connection member according to a preferred embodiment of thepresent invention, after dropping the battery packs;

FIGS. 6 and 7 are perspective views typically illustrating a process forassembling a battery pack according to a preferred embodiment of thepresent invention;

FIG. 8 is an enlarged perspective view illustrating a connection memberused in FIG. 6;

FIG. 9 is a typical plan view of the connection member used in FIG. 6;

FIG. 10 is a perspective view illustrating a connection member accordingto another preferred embodiment of the present invention;

FIG. 11 is a vertical sectional view of the connection member shown inFIG. 10;

FIG. 12 is a perspective view illustrating a connection member accordingto a modification;

FIG. 13 is an enlarged perspective view illustrating an example of aconnection member used in FIG. 6;

FIG. 14 is a typical plan view of the example of the connection memberused in FIG. 6;

FIG. 15 is a typical plan view illustrating a connection memberaccording to another preferred embodiment of the present invention;

FIG. 16 is a vertical sectional view taken along line E-E of FIG. 15with an enlarged view of a part F;

FIGS. 17 and 18 are perspective views respectively illustratingelectrode terminals having coupling openings according to otherembodiments of the present invention;

FIGS. 19 and 20 are perspective views respectively illustratingconnection members according to other preferred embodiments of thepresent invention;

FIG. 21 is a plan view typically illustrating a connection memberaccording to another preferred embodiment of the present invention;

FIG. 22 is a typical sectional view of the connection member shown inFIG. 21;

FIG. 23 is a plan view typically illustrating a connection memberaccording to another preferred embodiment of the present invention;

FIG. 24 is a typical sectional view of the connection member shown inFIG. 23;

FIG. 25 is a perspective view of the connection member shown in FIG. 23;

FIG. 26 is a plan view typically illustrating a connection memberaccording to a further preferred embodiment of the present invention;and

FIG. 27 is a typical sectional view of the connection member shown inFIG. 26.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Now, preferred embodiments of the present invention will be described indetail with reference to the accompanying drawings. It should be noted,however, that the scope of the present invention is not limited by theillustrated embodiments.

FIGS. 6 and 7 are perspective views typically illustrating a process forassembling a battery pack according to a preferred embodiment of thepresent invention.

Referring to these drawings, the battery pack 400 is constructed in astructure in which a plurality of cylindrical battery cells 302, 304,306, and 308 are electrically connected to one another via predeterminedconnection members 100 and 102 in a pack case 200 having no partition.

Specifically, two kinds of connection members 100 and 102 and fourcylindrical battery cells 302, 304, 306, and 308 are located in areceiving part of the pack case 200, while the four cylindrical batterycells 302, 304, 306, and 308 are brought into tight contact with oneanother, such that cathode terminals are connected to protrudingcoupling parts 130 of the connection members 100 in a mechanicalcoupling manner.

Consequently, the cathode terminals of the cylindrical battery cells 306and 308 are connected to the connection members 100 having theprotruding coupling parts 130 in a mechanical coupling manner, while thecathode terminals of the cylindrical battery cells 306 and 308 areelastically pressed, and anode terminals of the cylindrical batterycells 302 and 304 are connected to the connection members 100 in aphysical connection manner, whereby it is possible to easily assemblethe battery pack and stably maintain the connection structure betweenthe electrode terminals of the battery cells.

Also, the connection member 102, which includes no protruding couplingpart 130, is mounted at the region where anode terminals of thecylindrical battery cells 306 and 308 come into contact with a sidewallof the pack case, whereby the anode terminals of the cylindrical batterycells 306 and 308, arranged in the lateral direction, are electricallyconnected in parallel to each other.

The structure of the battery pack 400 after the assembly is shown inFIG. 7. Referring to FIG. 7, the battery pack 400 is constructed in a2P-2S plane-type structure in which the two cylindrical battery cells300 are arranged in contact with each other in the lateral direction,and, at the same time, the two cylindrical battery cells 300 arearranged in the longitudinal direction.

FIG. 8 is an enlarged perspective view illustrating the connectionmember 100 used in FIG. 6, and FIG. 9 is a typical plan view of theconnection member used in FIG. 6.

Referring to these drawings, the connection member 100 is constructed ina structure in which two terminal connection units A and B are connectedto each other, and a circuit connection terminal part 150 for connectionto an external circuit is included in the connection member 100.

Each of the terminal connection units includes an outer circumferentialcontact part 110, having a predetermined width, electrically connectedto an electrode terminal of a lower battery cell (not shown) in asurface contact manner, a bridge-type central contact part 160, andauxiliary connection parts 140 and 142 tapered upward and downward,respectively, from the inside of the outer circumferential contact part110.

The central contact part 160 includes upward protruding parts 120extending from the outer circumferential contact part 110 toward acentral axis 180 of each terminal connection unit, such that the upwardprotruding parts 120 are tapered upward, and protruding coupling parts130 connected to the respective upward protruding parts 120 via bridges190 while protruding upward.

The outer circumferential contact part 110 is electrically connected tothe electrode terminal (not shown) of the lower battery cell in asurface contact manner, while contacting the electrode terminal of thelower battery cell along the outer circumference of the electrodeterminal of the lower battery cell, to minimize the change of resistanceat the contact region against an external force and restrain apossibility that the electrode terminal of the lower battery cell isdepressed. The outer circumferential contact part 110 is constructed ina ring-shaped structure corresponding to the shape of the electrodeterminal of the lower battery cell such that the outer circumferentialcontact part 110 can contact the electrode terminal of the lower batterycell in a surface contact manner.

The central contact part 160 protrudes such that the central contactpart 160 can be located higher than the outer circumferential contactpart 110. The central contact part 160 is constructed in an elasticbridge structure to exhibit high contact elasticity and to disperseexternal impact when the external impact is applied to the centralcontact part 160, thereby minimizing the amount of the impacttransmitted to the outer circumferential contact part 110.

The top of each upward protruding part 120 protrudes upward in thevertical sectional shape thereof. Also, each protruding coupling part130 is provided at the inside thereof with a coupling protrusion 132,which protrudes toward the central axis 180 of the terminal connectionunit. The coupling protrusion 132 of each protruding coupling part 130prevents the connection member from separating from the upper batterycell (not shown) after the connection member is coupled to apredetermined region of the electrode terminal of the upper batterycell. At this time, the upward protruding parts 120 and the bridges 190contact the central region of the electrode terminal of the upperbattery cell, whereby the electrical connection is achieved.

The four bridges 190 connecting the protruding coupling parts 130 andthe upward protruding parts 120 are radially arranged in a symmetricalstructure. Specifically, the bridges 190, arranged at predeterminedintervals, connect the upward protruding parts 120 and the protrudingcoupling parts 130. The bridges 190 protrude upward.

Also, the four auxiliary connection parts 140 are tapered upward fromthe outer circumferential contact part 110 in a space defined betweenthe respective bridges 190 and the outer circumferential contact part110. The other four auxiliary connection parts 142 are tapered downwardfrom the outer circumferential contact part 110. Ends of the respectiveauxiliary connection parts 140 are bent downward, i.e., in the directionopposite to the upward taper direction of the corresponding auxiliaryconnection parts, and ends of the respective auxiliary connection parts142 are bent upward, i.e., in the direction opposite to the downwardtaper direction of the corresponding auxiliary connection parts.Consequently, when the connection member 100 is mounted to the cathodeor anode terminals of the lower battery cell (not shown), the auxiliaryconnection parts 140 and 142 are connected to the electrode terminals ofthe lower battery cells or the upper battery cells while beingelastically pressed.

Although the auxiliary connection parts 140 and 142 exhibit somewhat lowmodulus of elasticity, the four auxiliary connection parts 140 and thefour auxiliary connection parts 142 are independently connected to theelectrode terminal of the battery cell. Consequently, the auxiliaryconnection parts 140 and 142 prevent the occurrence of an instantaneousshort circuit of the battery cell due to an external factor, such asvibration, thereby continuously maintaining the electrical connectionbetween the battery cells.

FIG. 10 is a perspective view illustrating a connection member accordingto another preferred embodiment of the present invention, FIG. 11 is avertical sectional view of the connection member shown in FIG. 10, andFIG. 12 is a perspective view illustrating a connection member accordingto a modification.

Referring to these drawings, the connection member 100 a includes twoterminal connection units Aa and Ba connected to each other and circuitconnection terminal parts 170 a for connection to an external circuit.

Each of the terminal connection units includes an outer circumferentialcontact part 110 a electrically connected to an electrode terminal of alower battery cell (not shown) in a surface contact manner, the outercircumferential contact part 110 a having a predetermined width c, acentral contact part 160 a protruding from the outer circumferentialcontact part 110 a toward a central axis 180 of each terminal connectionunit, and auxiliary connection parts 140 and 142 protruding from theinside end of the outer circumferential contact part 110 a.

The central contact part 160 a includes upward protruding parts 120 aconfigured to be tapered upward, protruding coupling parts 130 aprotruding upward from the respective upward protruding parts 120 a to apredetermined height d, and a depressed contact part 134 a disposed onthe central axis 180 a of each terminal connection unit such that thedepressed contact part 134 a is depressed to a predetermined depth efrom upper end surfaces of the respective protruding coupling parts 130a, the depressed contact part 134 a being electrically connected to anelectrode terminal of an upper battery cell (not shown).

The outer circumferential contact part 110 a is formed in the shape of aconcentric circle corresponding to the outside of the electrode terminalof the lower battery cell.

The respective upward protruding parts 120 a have a width f equivalentto approximately 30% of the radius C of each terminal connection unit.The respective upward protruding parts 120 a are tapered upward at apredetermined angle a toward the central axis 180 a of each terminalconnection unit from the outer circumferential contact part 110 a.Consequently, the elastic connection between the outer circumferentialcontact part 110 a and the electrode terminal of the lower battery cellis maintained by the upward protruding parts 120 a.

The height d of the respective protruding coupling parts 130 a isapproximately 50% of the total height D of the connection member 100 a.The respective protruding coupling parts 130 a are formed approximatelyin the vertical sectional shape of “∩” Also, each protruding couplingpart 130 a is provided at the inside thereof with a coupling protrusion132 a, which protrudes toward the central axis 180 a of each terminalconnection unit. Consequently, the protruding coupling parts 130 aprevent the connection member from separating from the upper batterycell after the connection member is coupled to a predetermined region ofthe electrode terminal of the upper battery cell. At this time, thedepressed contact part 134 a contacts the central region of theelectrode terminal of the upper battery cell, whereby the electricalconnection is achieved.

The protruding coupling parts 130 a are constructed in a structure inwhich four bridges 190 a connecting the respective upward protrudingparts 120 a and the depressed contact part 134 a are radially arrangedin a symmetrical fashion. Specifically, the bridges 190 a, arranged atpredetermined intervals, connect the respective upward protruding parts120 a and the depressed contact part 134 a. The bridges 190 a protrudeupward to constitute the respective protruding coupling parts 330.

The auxiliary connection parts 140 a are inclined at a predeterminedangle b toward the central axis 180 a of each terminal connection unit.Lower ends 144 a of the respective auxiliary connection parts 140 aextend to a height lower than that of the outer circumferential contactpart 110 a. Consequently, when the connection member 100 a is mounted tothe anode terminal of the lower battery cell (not shown), the auxiliaryconnection parts 140 a are connected to the electrode terminal of thelower battery cell while being elastically pressed.

A connection member 100 a′ of FIG. 12 is different from the connectionmember 100 a of FIG. 10 in that a circuit connection terminal part isformed in the shape of a strip extending from one of the outercircumferential contact parts 110 a, two or more downward extensions 110a′ are formed at the outer circumference of each outer circumferentialcontact part 110 a to partially cover the upper-end sides of lowerbattery cells, and coupling protrusions 130 a′ protrude from the innersides of the protruding coupling parts 130 a in the shape of ahemispherical protrusion.

The downward extensions 110 a′ are constructed in a structure topartially cover the upper-end sides of the lower battery cells.Consequently, the downward extensions 312 prevent the connection member100 a′ from deviating in position from the lower battery cells due toexternal impact and maintain the secure coupling between the connectionmember 100 a′ and the lower battery cells.

This structure enables the connection member to be connected to theupper battery cells and the lower battery cells in a coupling fashion.That is, the protruding coupling parts of the connection member arecoupled to the electrode terminals of the upper battery cells, and thedownward extensions of the connection member are coupled to theelectrode terminals of the lower battery cells. Consequently, theconnection member is coupled to both the upper and lower battery cells.

FIG. 13 is an enlarged perspective view illustrating an example of theconnection member 102 used in FIG. 6, and FIG. 14 is a typical plan viewof the example of the connection member used in FIG. 6.

Referring to these drawings, the connection member 100 b is constructedin a structure in which two terminal connection units Ab and Bb areconnected to each other, and the connection member is provided at oneside thereof with a side extension part 150 b where a circuit connectionterminal part 152 b for connection to an external circuit is located.

Each of the terminal connection units includes an outer circumferentialcontact part 110 b, having a predetermined width, electrically connectedto an electrode terminal of a lower battery cell (not shown) in asurface contact manner, a bridge-type central contact part 130 bextending from the outer circumferential contact part 110 b toward acentral axis 180 b of each terminal connection unit such that thecentral contact part 130 b is tapered upward, and auxiliary connectionparts 140 b tapered downward from the inside of the outercircumferential contact part 110 b.

The central contact part 130 b has a predetermined height h less thanthe total height H of the connection member 100 b. The four bridges ofthe central contact part 130 b are symmetrically arranged in across-shaped structure.

Also, the four auxiliary connection parts 140 b, which are arrangedradially about the central axis 180 b of each terminal connection unitin a symmetrical structure, are tapered downward from the outercircumferential contact part 110 b in a space defined between thecentral contact part 130 b and the outer circumferential contact part110 b. Ends 144 b of the respective auxiliary connection parts 140 b arebent upward, i.e., in the direction opposite to the downward taperdirection of the corresponding auxiliary connection parts. Consequently,when the connection member 100 b is mounted to the anode terminals ofthe lower battery cells (not shown), the auxiliary connection parts 140b are connected to the electrode terminals of the battery cells locatedbelow the connection member 100 b while being elastically pressed.

FIG. 15 is a typical plan view illustrating a connection memberaccording to another preferred embodiment of the present invention, andFIG. 16 is a vertical sectional view taken along line E-E of FIG. 15with an enlarged view of a part F.

Referring to these drawings, the connection member 100 c is a singlemetal plate constructed in a 2P structure in which two terminalconnection units Ac and Bc are connected to each other. Each of theterminal connection units is constructed in a dish-shaped discstructure. Each of the terminal connection units includes an outercircumferential contact part 110 c and a central contact part 160 c,which form a concentric circle structure.

The outer circumferential contact part 110 c corresponds to the circularoutside of a battery cell terminal (not shown) such that the outercircumferential contact part 110 c contacts the battery cell terminal atthe outer circumference thereof.

The central contact part 160 c includes a pressing part 130 c tapered ata predetermined inclination toward a central axis of each terminalconnection unit to provide an elastic force and a depressed part 140 cformed at the central part of the pressing part 130 c. At each sideextension part 152 c of the connection member 100 c is located a circuitconnection terminal part 150 c for connection to an external circuit.

A battery cell is elastically connected to the central contact part 160c, which has the predetermined inclination. At the pressing part 130 cof the central contact part 160 c are formed cut-off parts 132 carranged about the central axis of each terminal connection unit in theshape of a whirlpool. Consequently, it is possible to control theelastic force of the central contact part 160 c to a desired degree.

FIGS. 17 and 18 are perspective views respectively illustratingelectrode terminals having coupling openings according to otherembodiments of the present invention.

Referring to these drawings, the electrode terminal 100 d; 101 daccording to the present invention has gas discharge ports 120 d formedat a protrusion thereof in the circumferential direction. The electrodeterminal 100 d; 101 d is provided at the central region thereof with acoupling opening 110 d; 111 d in which an electrical connection memberis coupled in a mechanical coupling manner. However, when the couplingopening 110 d; 111 d also functions as a gas discharge port, it is notnecessary to additionally form the gas discharge ports 120 d.

The coupling opening 110 d is formed, for example, approximately in across-shaped structure (see the structure of the electrode terminal 100d), and the coupling opening 111 d is formed, for example, in astructure in which two arc-shaped slits are disposed in a symmetricalfashion (see the structure of the electrode terminal 101 d).Consequently, the electrical connection member and the coupling partsthereof may be formed in various structures depending upon the structureor the shape of the coupling opening 110 d; 111 d of the electrodeterminal.

Specifically, coupling parts formed in a shape corresponding to theshape of a long side of the cross-shaped coupling opening 110 d areinserted into the coupling opening 110 s of the electrode terminal, andare then rotated 90 degrees, whereby the elastic coupling between theelectrical connection member and the electrode terminal 100 d isachieved.

On the other hand, coupling parts horizontally bent in the longitudinaldirection of the slits such that the coupling parts are constructedapproximately in the vertical sectional shape of “

” are inserted into the coupling opening 111 d constructed in astructure in which the two arc-shaped slits are disposed in asymmetrical fashion, and are then rotated in the direction in which thecoupling parts are bent, whereby the elastic coupling between theelectrical connection member and the electrode terminal is achieved.

FIGS. 19 and 20 are perspective views respectively illustratingconnection members according to other preferred embodiments of thepresent invention.

Referring first to FIG. 19, the connection member 100 e according to thepresent invention is constructed in a structure in which two terminalconnection units Ae and Be are connected to each other, and a circuitconnection terminal part 150 e for connection to an external circuit isincluded in the connection member 100 e.

Each of the terminal connection units Ae and Be includes an outercircumferential contact part 110 e, having a predetermined width,electrically connected to an electrode terminal of a lower battery cell(not shown), coupling parts 130 e formed on upward protruding parts 120e tapered upward from the outer circumferential contact part 110 etoward a central axis of each terminal connection unit, and auxiliaryconnection parts 140 e and 142 e tapered upward and downward,respectively, from the inside of the outer circumferential contact part110 e.

The width of the outer circumferential contact part 110 e contacting theelectrode terminal of the lower battery cell is approximately 10% of theradius of each terminal connection unit. The outer circumferentialcontact part 110 e is formed in the shape of a concentric circlecorresponding to the outside of the electrode terminal of the lowerbattery cell.

The coupling parts 130 e are constructed in a structure in which ends ofthe respective coupling parts 130 e are bent outward. Consequently, whenthe coupling parts 130 e are inserted into the coupling opening 110 d ofthe electrode terminal 100 d as shown in FIG. 17 and are then rotated,the electrical connection between the connection member and theelectrode terminal is achieved while the coupling between the connectionmember and the electrode terminal is securely maintained.

Also, the four auxiliary connection parts 140 e are inclined upward fromthe outer circumferential contact part 110 e by a predetermined height,and the other four auxiliary connection parts 142 e are tapered downwardfrom the outer circumferential contact part 110 e by a predetermineddepth. Ends of the respective auxiliary connection parts 140 e are bentdownward, i.e., in the direction opposite to the upward taper directionof the corresponding auxiliary connection parts, and ends of therespective auxiliary connection parts 142 e are bent upward, i.e., inthe direction opposite to the downward taper direction of thecorresponding auxiliary connection parts. Consequently, when theconnection member 100 e is mounted to the cathode or anode terminals ofthe lower battery cell (not shown), the auxiliary connection parts 140 eand 142 e are connected to the electrode terminals of the lower batterycells or the upper battery cells while being elastically pressed.

Although the auxiliary connection parts 140 e and 142 e exhibit somewhatlow modulus of elasticity, the four auxiliary connection parts 140 e andthe four auxiliary connection parts 142 e are independently connected tothe electrode terminal of the lower battery cell. Consequently, theauxiliary connection parts 140 e and 142 e prevent the occurrence of aninstantaneous short circuit of the battery cell due to an externalfactor, such as vibration, thereby continuously maintaining theelectrical connection between the battery cells.

The connection member 101 e of FIG. 20 is identical in construction tothe connection member of FIG. 19 except that the connection member 101 eof FIG. 20 includes a single terminal connection unit. That is, theterminal connection unit of the connection member 101 e of FIG. 20includes an outer circumferential contact part 110 e, upward protrudingparts 120 e, protruding coupling parts 130 e and 132 e, and auxiliaryconnection parts 140 e and 142 e, and a circuit connection terminal part150 e, all of which are identical to those of FIG. 19. Accordingly, adetailed description of the same components will not be given.

FIG. 21 is a plan view typically illustrating a connection memberaccording to another preferred embodiment of the present invention, andFIG. 22 is a typical sectional view of the connection member shown inFIG. 21.

Referring to these drawings, the connection member 100 f includes twoterminal connection units Af and Bf connected to each other and sideextension parts 150 f where circuit connection terminal parts forconnection to an external circuit are located. Here, the externalcircuit connection terminal parts may be input and output terminals forpower supply, detection terminals for voltage detection, or combinationsthereof.

Each of the terminal connection units includes an outer circumferentialcontact part 110 f formed in the shape corresponding to the externalshape of an electrode terminal of a battery cell and contacting anelectrode terminal of a lower battery cell (not shown) at a regionadjacent to the outer circumference of the connection member, the outercircumferential contact part 110 f having a predetermined width, anupward protruding part 120 f extending from the outer circumferentialcontact part 110 f toward a central axis of each terminal connectionunit such that the upward protruding part 120 f is tapered upward, and acentral contact part 130 f contacting an electrode terminal of a batterycell (not shown) located above the connection member 100 f.

At the upward protruding part 120 f and the central contact part 130 fare formed cut-out parts 140 f constructed in a bridge structure inwhich the cut-out parts 140 f extend from the upward protruding part 120f to the central contact part 130 f and successively extend from thecentral contact part 130 f to the upward protruding part 120 f.

The central contact part 130 f has a contact interface w of a sizeequivalent to approximately 60% of the surface area W of the electrodeterminal of the upper battery cell (not shown).

Meanwhile, the outer circumferential contact part 110 f and the centralcontact part 130 f are electrically connected to an anode terminal (notshown) of the lower battery cell and a cathode terminal (not shown) ofthe upper battery cell, respectively, in a physical contact manner.

Each cut-out part 140 f is constructed in a structure in which a cut-outstart point 141 f and a cut-out end point 143 f form an angle a ofapproximately 90 degrees under a condition that each cut-out part 140 fdoes not reach the central axis 131 f of the connection member 100 f.Also, the cut-out parts 140 f are radially arranged in a symmetricalstructure in which the four cut-out parts 140 f are symmetricallydisposed about the central axis 131 f of the connection member 100 f.And the distance d1 between the central axis 131 f of the connectionmember 100 f and a region of the connection member 100 f where theconnection member 100 f is the most adjacent to the central axis 131 fof the connection member 100 f is approximately 20% of the width d2 ofthe central contact part 130 f.

Also, the respective cut-out parts 140 f are cut out with a width d3equivalent to approximately 130% of the thickness T of the connectionmember. And the respective cut-out parts 140 f pass through theuppermost portion 121 f of the upward protruding part 120 f.

By the provision of the cut-out parts 140 f, it is possible for theupward protruding part 120 f to exhibit appropriate flexibility as wellas elasticity. Consequently, it is possible to prevent the occurrence ofan instantaneous short circuit of the battery cell due to an externalfactor, such as vibration, thereby continuously maintaining theelectrical connection between the battery cells.

FIG. 23 is a plan view typically illustrating a connection memberaccording to another preferred embodiment of the present invention, FIG.24 is a typical sectional view of the connection member shown in FIG.23, and FIG. 25 is a perspective view of the connection member shown inFIG. 23.

Referring to these drawings, the connection member 100 g includes twoterminal connection units Ag and Bg connected to each other and sideextension parts 150 g where circuit connection terminal parts forconnection to an external circuit are located.

Each of the terminal connection units includes an outer circumferentialcontact part 110 g connected to an electrode terminal of a lower batterycell (not shown), an upward protruding part 120 g extending from theouter circumferential contact part 110 g toward a central axis of eachterminal connection unit such that the upward protruding part 120 g istapered upward, and a central contact part 130 g contacting an electrodeterminal of a battery cell (not shown) located above the connectionmember 100 g. At the upward protruding part 120 g and the centralcontact part 130 g are formed cut-out parts 140 g constructed in a slitstructure in which the cut-out parts 440 extend from the upwardprotruding part 120 g to the central contact part 130 g and successivelyextend from the central contact part 130 g to the upward protruding part120 g.

FIG. 26 is a plan view typically illustrating a connection memberaccording to a further preferred embodiment of the present invention,and FIG. 27 is a typical sectional view of the connection member shownin FIG. 26.

Referring to these drawings, the connection member 100 h includes twoterminal connection units Ah and Bh connected to each other and sideextension parts 150 h where circuit connection terminal parts forconnection to an external circuit are located.

Each of the terminal connection units includes an outer circumferentialcontact part 110 h contacting an electrode terminal of a lower batterycell (not shown), an upward protruding part 120 h extending from theouter circumferential contact part 110 h toward a central axis of eachterminal connection unit such that the upward protruding part 120 h istapered upward, and a central contact part 130 h contacting an electrodeterminal of a battery cell (not shown) located above the connectionmember 100 h.

At the upward protruding part 120 h and the central contact part 130 hare formed cut-out parts 140 h constructed in a slit structure in whicheach cut-out part 140 h extends from one cut-out start point 141 h ofthe upward protruding part 120 h to the central contact part 130 h andsuccessively extends from the central contact part 130 h to two cut-outend points 142 c and 143 h of the upward protruding part 120 h.

By the provision of the cut-out parts 140 h, it is possible to controlthe elasticity of the upward protruding part 120 h to a desired degree.

INDUSTRIAL APPLICABILITY

As apparent from the above description, the connection member forsecondary batteries according to the present invention does not need awelding or soldering process for electrical connection between electrodeterminals of battery cells. Consequently, it is possible to prevent theoccurrence of short circuits of the battery cells, which may be causedduring welding, and to greatly reduce the defective production ratio.Also, it is possible to minimize the change in resistance at theconnection regions through the stable coupling structure between theelectrode terminals of the secondary battery cells and to greatlyimprove the production efficiency. In addition, when an external force,such as dropping or vibration, is applied to a battery pack, it ispossible to protect the battery cells from the external force.Furthermore, it is possible to maintain the stable connection of thebattery pack even when in use for a long period of time, while notcausing the increase in size of the battery pack although the batterypack is constructed in an electrically connection structure not usingwelding.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

What is claimed is:
 1. A connection member for secondary batteries toachieve the electrical connection in a battery pack including two ormore cylindrical secondary batteries in a physical contact manner, theconnection member comprises a terminal connection unit for connectingthe battery cells arranged in the longitudinal direction in series toeach other, the terminal connection unit comprising: (a) an outercircumferential contact part configured to correspond to the externalshape of an electrode terminal of a lower battery cell located below theconnection member, the outer circumferential contact part contacting theelectrode terminal of the lower battery cell at a region adjacent to theouter circumference of the electrode terminal, the outer circumferentialcontact part having a predetermined width; (b) an upward protruding parttapered upward from the outer circumferential contact part toward acentral axis of the terminal connection unit for elastically supportingthe lower battery cell; and (c) a central contact part contacting anelectrode terminal of an upper battery cell located above the connectionmember, the terminal connection unit being constructed in a structure inwhich cut-out parts are formed at the upward protruding part and thecentral contact part, such that the cut-out parts extend from the upwardprotruding part to the central contact part and successively extend fromthe central contact part to the upward protruding part, to increase anelastically supporting force with respect to the electrode terminal ofthe battery cell.
 2. The connection member according to claim 1, whereineach of the cut-out parts is constructed in a structure in which acut-out start point and a cut-out end point form an angle of 20 to 160degrees under a condition that each of the cut-out parts does not reachthe central axis of the connection member.
 3. The connection memberaccording to claim 1, wherein two or more terminal connection units areconnected to each other to simultaneously achieve the connection inseries between the battery cells arranged in the longitudinal directionand the connection in parallel between battery cells arranged in thelateral direction.
 4. The connection member according to claim 1,wherein two or more terminal connection units are connected to eachother to simultaneously achieve the connection in series between thebattery cells arranged in the longitudinal direction and the connectionin parallel between battery cells arranged in the lateral direction. 5.The connection member according to claim 1, wherein the terminalconnection unit is provided at one side thereof with a circuitconnection terminal part.
 6. A battery pack constructed in a structurein which a connection member for secondary batteries according to claim1 is mounted between electrode terminals of battery cells to achieve theelectrical connection between the battery cells.
 7. A laptop computerincluding a battery pack according to claim 6 as a power source.